dm: i2c: Add a uclass for I2C

The uclass implements the same operations as the current I2C framework but
makes some changes to make it fit driver model better:

- Remove the chip address from API calls
- Remove the address length from API calls
- Remove concept of 'current' I2C bus
- Drop all existing init functions

Acked-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/i2c/Makefile

@@ -4,6 +4,7 @@
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #
+obj-$(CONFIG_DM_I2C) += i2c-uclass.o
 
 obj-$(CONFIG_SYS_I2C_ADI) += adi_i2c.o
 obj-$(CONFIG_I2C_MV) += mv_i2c.o

drivers/i2c/i2c-uclass.c

@@ -0,0 +1,466 @@
+/*
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <malloc.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define I2C_MAX_OFFSET_LEN	4
+
+/**
+ * i2c_setup_offset() - Set up a new message with a chip offset
+ *
+ * @chip:	Chip to use
+ * @offset:	Byte offset within chip
+ * @offset_buf:	Place to put byte offset
+ * @msg:	Message buffer
+ * @return 0 if OK, -EADDRNOTAVAIL if the offset length is 0. In that case the
+ * message is still set up but will not contain an offset.
+ */
+static int i2c_setup_offset(struct dm_i2c_chip *chip, uint offset,
+			    uint8_t offset_buf[], struct i2c_msg *msg)
+{
+	int offset_len;
+
+	msg->addr = chip->chip_addr;
+	msg->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
+	msg->len = chip->offset_len;
+	msg->buf = offset_buf;
+	if (!chip->offset_len)
+		return -EADDRNOTAVAIL;
+	assert(chip->offset_len <= I2C_MAX_OFFSET_LEN);
+	offset_len = chip->offset_len;
+	while (offset_len--)
+		*offset_buf++ = offset >> (8 * offset_len);
+
+	return 0;
+}
+
+static int i2c_read_bytewise(struct udevice *dev, uint offset,
+			     uint8_t *buffer, int len)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+	struct udevice *bus = dev_get_parent(dev);
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct i2c_msg msg[2], *ptr;
+	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
+	int ret;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if (i2c_setup_offset(chip, offset + i, offset_buf, msg))
+			return -EINVAL;
+		ptr = msg + 1;
+		ptr->addr = chip->chip_addr;
+		ptr->flags = msg->flags | I2C_M_RD;
+		ptr->len = 1;
+		ptr->buf = &buffer[i];
+		ptr++;
+
+		ret = ops->xfer(bus, msg, ptr - msg);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int i2c_write_bytewise(struct udevice *dev, uint offset,
+			     const uint8_t *buffer, int len)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+	struct udevice *bus = dev_get_parent(dev);
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct i2c_msg msg[1];
+	uint8_t buf[I2C_MAX_OFFSET_LEN + 1];
+	int ret;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if (i2c_setup_offset(chip, offset + i, buf, msg))
+			return -EINVAL;
+		buf[msg->len++] = buffer[i];
+
+		ret = ops->xfer(bus, msg, 1);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int i2c_read(struct udevice *dev, uint offset, uint8_t *buffer, int len)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+	struct udevice *bus = dev_get_parent(dev);
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct i2c_msg msg[2], *ptr;
+	uint8_t offset_buf[I2C_MAX_OFFSET_LEN];
+	int msg_count;
+
+	if (!ops->xfer)
+		return -ENOSYS;
+	if (chip->flags & DM_I2C_CHIP_RD_ADDRESS)
+		return i2c_read_bytewise(dev, offset, buffer, len);
+	ptr = msg;
+	if (!i2c_setup_offset(chip, offset, offset_buf, ptr))
+		ptr++;
+
+	if (len) {
+		ptr->addr = chip->chip_addr;
+		ptr->flags = chip->flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
+		ptr->flags |= I2C_M_RD;
+		ptr->len = len;
+		ptr->buf = buffer;
+		ptr++;
+	}
+	msg_count = ptr - msg;
+
+	return ops->xfer(bus, msg, msg_count);
+}
+
+int i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer, int len)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+	struct udevice *bus = dev_get_parent(dev);
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct i2c_msg msg[1];
+
+	if (!ops->xfer)
+		return -ENOSYS;
+
+	if (chip->flags & DM_I2C_CHIP_WR_ADDRESS)
+		return i2c_write_bytewise(dev, offset, buffer, len);
+	/*
+	 * The simple approach would be to send two messages here: one to
+	 * set the offset and one to write the bytes. However some drivers
+	 * will not be expecting this, and some chips won't like how the
+	 * driver presents this on the I2C bus.
+	 *
+	 * The API does not support separate offset and data. We could extend
+	 * it with a flag indicating that there is data in the next message
+	 * that needs to be processed in the same transaction. We could
+	 * instead add an additional buffer to each message. For now, handle
+	 * this in the uclass since it isn't clear what the impact on drivers
+	 * would be with this extra complication. Unfortunately this means
+	 * copying the message.
+	 *
+	 * Use the stack for small messages, malloc() for larger ones. We
+	 * need to allow space for the offset (up to 4 bytes) and the message
+	 * itself.
+	 */
+	if (len < 64) {
+		uint8_t buf[I2C_MAX_OFFSET_LEN + len];
+
+		i2c_setup_offset(chip, offset, buf, msg);
+		msg->len += len;
+		memcpy(buf + chip->offset_len, buffer, len);
+
+		return ops->xfer(bus, msg, 1);
+	} else {
+		uint8_t *buf;
+		int ret;
+
+		buf = malloc(I2C_MAX_OFFSET_LEN + len);
+		if (!buf)
+			return -ENOMEM;
+		i2c_setup_offset(chip, offset, buf, msg);
+		msg->len += len;
+		memcpy(buf + chip->offset_len, buffer, len);
+
+		ret = ops->xfer(bus, msg, 1);
+		free(buf);
+		return ret;
+	}
+}
+
+/**
+ * i2c_probe_chip() - probe for a chip on a bus
+ *
+ * @bus:	Bus to probe
+ * @chip_addr:	Chip address to probe
+ * @flags:	Flags for the chip
+ * @return 0 if found, -ENOSYS if the driver is invalid, -EREMOTEIO if the chip
+ * does not respond to probe
+ */
+static int i2c_probe_chip(struct udevice *bus, uint chip_addr,
+			  enum dm_i2c_chip_flags chip_flags)
+{
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct i2c_msg msg[1];
+	int ret;
+
+	if (ops->probe_chip) {
+		ret = ops->probe_chip(bus, chip_addr, chip_flags);
+		if (!ret || ret != -ENOSYS)
+			return ret;
+	}
+
+	if (!ops->xfer)
+		return -ENOSYS;
+
+	/* Probe with a zero-length message */
+	msg->addr = chip_addr;
+	msg->flags = chip_flags & DM_I2C_CHIP_10BIT ? I2C_M_TEN : 0;
+	msg->len = 0;
+	msg->buf = NULL;
+
+	return ops->xfer(bus, msg, 1);
+}
+
+static int i2c_bind_driver(struct udevice *bus, uint chip_addr,
+			   struct udevice **devp)
+{
+	struct dm_i2c_chip chip;
+	char name[30], *str;
+	struct udevice *dev;
+	int ret;
+
+	snprintf(name, sizeof(name), "generic_%x", chip_addr);
+	str = strdup(name);
+	ret = device_bind_driver(bus, "i2c_generic_chip_drv", str, &dev);
+	debug("%s:  device_bind_driver: ret=%d\n", __func__, ret);
+	if (ret)
+		goto err_bind;
+
+	/* Tell the device what we know about it */
+	memset(&chip, '\0', sizeof(chip));
+	chip.chip_addr = chip_addr;
+	chip.offset_len = 1;	/* we assume */
+	ret = device_probe_child(dev, &chip);
+	debug("%s:  device_probe_child: ret=%d\n", __func__, ret);
+	if (ret)
+		goto err_probe;
+
+	*devp = dev;
+	return 0;
+
+err_probe:
+	device_unbind(dev);
+err_bind:
+	free(str);
+	return ret;
+}
+
+int i2c_get_chip(struct udevice *bus, uint chip_addr, struct udevice **devp)
+{
+	struct udevice *dev;
+
+	debug("%s: Searching bus '%s' for address %02x: ", __func__,
+	      bus->name, chip_addr);
+	for (device_find_first_child(bus, &dev); dev;
+			device_find_next_child(&dev)) {
+		struct dm_i2c_chip store;
+		struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+		int ret;
+
+		if (!chip) {
+			chip = &store;
+			i2c_chip_ofdata_to_platdata(gd->fdt_blob,
+						    dev->of_offset, chip);
+		}
+		if (chip->chip_addr == chip_addr) {
+			ret = device_probe(dev);
+			debug("found, ret=%d\n", ret);
+			if (ret)
+				return ret;
+			*devp = dev;
+			return 0;
+		}
+	}
+	debug("not found\n");
+	return i2c_bind_driver(bus, chip_addr, devp);
+}
+
+int i2c_get_chip_for_busnum(int busnum, int chip_addr, struct udevice **devp)
+{
+	struct udevice *bus;
+	int ret;
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, busnum, &bus);
+	if (ret) {
+		debug("Cannot find I2C bus %d\n", busnum);
+		return ret;
+	}
+	ret = i2c_get_chip(bus, chip_addr, devp);
+	if (ret) {
+		debug("Cannot find I2C chip %02x on bus %d\n", chip_addr,
+		      busnum);
+		return ret;
+	}
+
+	return 0;
+}
+
+int i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
+	      struct udevice **devp)
+{
+	int ret;
+
+	*devp = NULL;
+
+	/* First probe that chip */
+	ret = i2c_probe_chip(bus, chip_addr, chip_flags);
+	debug("%s: bus='%s', address %02x, ret=%d\n", __func__, bus->name,
+	      chip_addr, ret);
+	if (ret)
+		return ret;
+
+	/* The chip was found, see if we have a driver, and probe it */
+	ret = i2c_get_chip(bus, chip_addr, devp);
+	debug("%s:  i2c_get_chip: ret=%d\n", __func__, ret);
+
+	return ret;
+}
+
+int i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+{
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct dm_i2c_bus *i2c = bus->uclass_priv;
+	int ret;
+
+	/*
+	 * If we have a method, call it. If not then the driver probably wants
+	 * to deal with speed changes on the next transfer. It can easily read
+	 * the current speed from this uclass
+	 */
+	if (ops->set_bus_speed) {
+		ret = ops->set_bus_speed(bus, speed);
+		if (ret)
+			return ret;
+	}
+	i2c->speed_hz = speed;
+
+	return 0;
+}
+
+/*
+ * i2c_get_bus_speed:
+ *
+ *  Returns speed of selected I2C bus in Hz
+ */
+int i2c_get_bus_speed(struct udevice *bus)
+{
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	struct dm_i2c_bus *i2c = bus->uclass_priv;
+
+	if (!ops->get_bus_speed)
+		return i2c->speed_hz;
+
+	return ops->get_bus_speed(bus);
+}
+
+int i2c_set_chip_flags(struct udevice *dev, uint flags)
+{
+	struct udevice *bus = dev->parent;
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+	int ret;
+
+	if (ops->set_flags) {
+		ret = ops->set_flags(dev, flags);
+		if (ret)
+			return ret;
+	}
+	chip->flags = flags;
+
+	return 0;
+}
+
+int i2c_get_chip_flags(struct udevice *dev, uint *flagsp)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+
+	*flagsp = chip->flags;
+
+	return 0;
+}
+
+int i2c_set_chip_offset_len(struct udevice *dev, uint offset_len)
+{
+	struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+
+	if (offset_len > I2C_MAX_OFFSET_LEN)
+		return -EINVAL;
+	chip->offset_len = offset_len;
+
+	return 0;
+}
+
+int i2c_deblock(struct udevice *bus)
+{
+	struct dm_i2c_ops *ops = i2c_get_ops(bus);
+
+	/*
+	 * We could implement a software deblocking here if we could get
+	 * access to the GPIOs used by I2C, and switch them to GPIO mode
+	 * and then back to I2C. This is somewhat beyond our powers in
+	 * driver model at present, so for now just fail.
+	 *
+	 * See https://patchwork.ozlabs.org/patch/399040/
+	 */
+	if (!ops->deblock)
+		return -ENOSYS;
+
+	return ops->deblock(bus);
+}
+
+int i2c_chip_ofdata_to_platdata(const void *blob, int node,
+				struct dm_i2c_chip *chip)
+{
+	chip->offset_len = 1;	/* default */
+	chip->flags = 0;
+	chip->chip_addr = fdtdec_get_int(gd->fdt_blob, node, "reg", -1);
+	if (chip->chip_addr == -1) {
+		debug("%s: I2C Node '%s' has no 'reg' property\n", __func__,
+		      fdt_get_name(blob, node, NULL));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int i2c_post_probe(struct udevice *dev)
+{
+	struct dm_i2c_bus *i2c = dev->uclass_priv;
+
+	i2c->speed_hz = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+				     "clock-frequency", 100000);
+
+	return i2c_set_bus_speed(dev, i2c->speed_hz);
+}
+
+int i2c_post_bind(struct udevice *dev)
+{
+	/* Scan the bus for devices */
+	return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
+}
+
+UCLASS_DRIVER(i2c) = {
+	.id		= UCLASS_I2C,
+	.name		= "i2c",
+	.per_device_auto_alloc_size = sizeof(struct dm_i2c_bus),
+	.post_bind	= i2c_post_bind,
+	.post_probe	= i2c_post_probe,
+};
+
+UCLASS_DRIVER(i2c_generic) = {
+	.id		= UCLASS_I2C_GENERIC,
+	.name		= "i2c_generic",
+};
+
+U_BOOT_DRIVER(i2c_generic_chip_drv) = {
+	.name		= "i2c_generic_chip_drv",
+	.id		= UCLASS_I2C_GENERIC,
+};

include/config_fallbacks.h

@@ -91,4 +91,10 @@
 #undef CONFIG_IMAGE_FORMAT_LEGACY
 #endif
 
+#ifdef CONFIG_DM_I2C
+# ifdef CONFIG_SYS_I2C
+#  error "Cannot define CONFIG_SYS_I2C when CONFIG_DM_I2C is used"
+# endif
+#endif
+
 #endif	/* __CONFIG_FALLBACKS_H */

include/dm/uclass-id.h

@@ -29,6 +29,8 @@ enum uclass_id {
 	UCLASS_SPI_FLASH,	/* SPI flash */
 	UCLASS_CROS_EC,	/* Chrome OS EC */
 	UCLASS_THERMAL,		/* Thermal sensor */
+	UCLASS_I2C,		/* I2C bus */
+	UCLASS_I2C_GENERIC,	/* Generic I2C device */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,

include/i2c.h

@@ -17,6 +17,355 @@
 #ifndef _I2C_H_
 #define _I2C_H_
 
+/*
+ * For now there are essentially two parts to this file - driver model
+ * here at the top, and the older code below (with CONFIG_SYS_I2C being
+ * most recent). The plan is to migrate everything to driver model.
+ * The driver model structures and API are separate as they are different
+ * enough as to be incompatible for compilation purposes.
+ */
+
+#ifdef CONFIG_DM_I2C
+
+enum dm_i2c_chip_flags {
+	DM_I2C_CHIP_10BIT	= 1 << 0, /* Use 10-bit addressing */
+	DM_I2C_CHIP_RD_ADDRESS	= 1 << 1, /* Send address for each read byte */
+	DM_I2C_CHIP_WR_ADDRESS	= 1 << 2, /* Send address for each write byte */
+};
+
+/**
+ * struct dm_i2c_chip - information about an i2c chip
+ *
+ * An I2C chip is a device on the I2C bus. It sits at a particular address
+ * and normally supports 7-bit or 10-bit addressing.
+ *
+ * To obtain this structure, use dev_get_parentdata(dev) where dev is the
+ * chip to examine.
+ *
+ * @chip_addr:	Chip address on bus
+ * @offset_len: Length of offset in bytes. A single byte offset can
+ *		represent up to 256 bytes. A value larger than 1 may be
+ *		needed for larger devices.
+ * @flags:	Flags for this chip (dm_i2c_chip_flags)
+ * @emul: Emulator for this chip address (only used for emulation)
+ */
+struct dm_i2c_chip {
+	uint chip_addr;
+	uint offset_len;
+	uint flags;
+#ifdef CONFIG_SANDBOX
+	struct udevice *emul;
+#endif
+};
+
+/**
+ * struct dm_i2c_bus- information about an i2c bus
+ *
+ * An I2C bus contains 0 or more chips on it, each at its own address. The
+ * bus can operate at different speeds (measured in Hz, typically 100KHz
+ * or 400KHz).
+ *
+ * To obtain this structure, use bus->uclass_priv where bus is the I2C
+ * bus udevice.
+ *
+ * @speed_hz: Bus speed in hertz (typically 100000)
+ */
+struct dm_i2c_bus {
+	int speed_hz;
+};
+
+/**
+ * i2c_read() - read bytes from an I2C chip
+ *
+ * To obtain an I2C device (called a 'chip') given the I2C bus address you
+ * can use i2c_get_chip(). To obtain a bus by bus number use
+ * uclass_get_device_by_seq(UCLASS_I2C, <bus number>).
+ *
+ * To set the address length of a devce use i2c_set_addr_len(). It
+ * defaults to 1.
+ *
+ * @dev:	Chip to read from
+ * @offset:	Offset within chip to start reading
+ * @buffer:	Place to put data
+ * @len:	Number of bytes to read
+ *
+ * @return 0 on success, -ve on failure
+ */
+int i2c_read(struct udevice *dev, uint offset, uint8_t *buffer,
+	     int len);
+
+/**
+ * i2c_write() - write bytes to an I2C chip
+ *
+ * See notes for i2c_read() above.
+ *
+ * @dev:	Chip to write to
+ * @offset:	Offset within chip to start writing
+ * @buffer:	Buffer containing data to write
+ * @len:	Number of bytes to write
+ *
+ * @return 0 on success, -ve on failure
+ */
+int i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer,
+	      int len);
+
+/**
+ * i2c_probe() - probe a particular chip address
+ *
+ * This can be useful to check for the existence of a chip on the bus.
+ * It is typically implemented by writing the chip address to the bus
+ * and checking that the chip replies with an ACK.
+ *
+ * @bus:	Bus to probe
+ * @chip_addr:	7-bit address to probe (10-bit and others are not supported)
+ * @chip_flags:	Flags for the probe (see enum dm_i2c_chip_flags)
+ * @devp:	Returns the device found, or NULL if none
+ * @return 0 if a chip was found at that address, -ve if not
+ */
+int i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
+	      struct udevice **devp);
+
+/**
+ * i2c_set_bus_speed() - set the speed of a bus
+ *
+ * @bus:	Bus to adjust
+ * @speed:	Requested speed in Hz
+ * @return 0 if OK, -EINVAL for invalid values
+ */
+int i2c_set_bus_speed(struct udevice *bus, unsigned int speed);
+
+/**
+ * i2c_get_bus_speed() - get the speed of a bus
+ *
+ * @bus:	Bus to check
+ * @return speed of selected I2C bus in Hz, -ve on error
+ */
+int i2c_get_bus_speed(struct udevice *bus);
+
+/**
+ * i2c_set_chip_flags() - set flags for a chip
+ *
+ * Typically addresses are 7 bits, but for 10-bit addresses you should set
+ * flags to DM_I2C_CHIP_10BIT. All accesses will then use 10-bit addressing.
+ *
+ * @dev:	Chip to adjust
+ * @flags:	New flags
+ * @return 0 if OK, -EINVAL if value is unsupported, other -ve value on error
+ */
+int i2c_set_chip_flags(struct udevice *dev, uint flags);
+
+/**
+ * i2c_get_chip_flags() - get flags for a chip
+ *
+ * @dev:	Chip to check
+ * @flagsp:	Place to put flags
+ * @return 0 if OK, other -ve value on error
+ */
+int i2c_get_chip_flags(struct udevice *dev, uint *flagsp);
+
+/**
+ * i2c_set_offset_len() - set the offset length for a chip
+ *
+ * The offset used to access a chip may be up to 4 bytes long. Typically it
+ * is only 1 byte, which is enough for chips with 256 bytes of memory or
+ * registers. The default value is 1, but you can call this function to
+ * change it.
+ *
+ * @offset_len:	New offset length value (typically 1 or 2)
+ */
+
+int i2c_set_chip_offset_len(struct udevice *dev, uint offset_len);
+/**
+ * i2c_deblock() - recover a bus that is in an unknown state
+ *
+ * See the deblock() method in 'struct dm_i2c_ops' for full information
+ *
+ * @bus:	Bus to recover
+ * @return 0 if OK, -ve on error
+ */
+int i2c_deblock(struct udevice *bus);
+
+/*
+ * Not all of these flags are implemented in the U-Boot API
+ */
+enum dm_i2c_msg_flags {
+	I2C_M_TEN		= 0x0010, /* ten-bit chip address */
+	I2C_M_RD		= 0x0001, /* read data, from slave to master */
+	I2C_M_STOP		= 0x8000, /* send stop after this message */
+	I2C_M_NOSTART		= 0x4000, /* no start before this message */
+	I2C_M_REV_DIR_ADDR	= 0x2000, /* invert polarity of R/W bit */
+	I2C_M_IGNORE_NAK	= 0x1000, /* continue after NAK */
+	I2C_M_NO_RD_ACK		= 0x0800, /* skip the Ack bit on reads */
+	I2C_M_RECV_LEN		= 0x0400, /* length is first received byte */
+};
+
+/**
+ * struct i2c_msg - an I2C message
+ *
+ * @addr:	Slave address
+ * @flags:	Flags (see enum dm_i2c_msg_flags)
+ * @len:	Length of buffer in bytes, may be 0 for a probe
+ * @buf:	Buffer to send/receive, or NULL if no data
+ */
+struct i2c_msg {
+	uint addr;
+	uint flags;
+	uint len;
+	u8 *buf;
+};
+
+/**
+ * struct i2c_msg_list - a list of I2C messages
+ *
+ * This is called i2c_rdwr_ioctl_data in Linux but the name does not seem
+ * appropriate in U-Boot.
+ *
+ * @msg:	Pointer to i2c_msg array
+ * @nmsgs:	Number of elements in the array
+ */
+struct i2c_msg_list {
+	struct i2c_msg *msgs;
+	uint nmsgs;
+};
+
+/**
+ * struct dm_i2c_ops - driver operations for I2C uclass
+ *
+ * Drivers should support these operations unless otherwise noted. These
+ * operations are intended to be used by uclass code, not directly from
+ * other code.
+ */
+struct dm_i2c_ops {
+	/**
+	 * xfer() - transfer a list of I2C messages
+	 *
+	 * @bus:	Bus to read from
+	 * @msg:	List of messages to transfer
+	 * @nmsgs:	Number of messages in the list
+	 * @return 0 if OK, -EREMOTEIO if the slave did not ACK a byte,
+	 *	-ECOMM if the speed cannot be supported, -EPROTO if the chip
+	 *	flags cannot be supported, other -ve value on some other error
+	 */
+	int (*xfer)(struct udevice *bus, struct i2c_msg *msg, int nmsgs);
+
+	/**
+	 * probe_chip() - probe for the presense of a chip address
+	 *
+	 * This function is optional. If omitted, the uclass will send a zero
+	 * length message instead.
+	 *
+	 * @bus:	Bus to probe
+	 * @chip_addr:	Chip address to probe
+	 * @chip_flags:	Probe flags (enum dm_i2c_chip_flags)
+	 * @return 0 if chip was found, -EREMOTEIO if not, -ENOSYS to fall back
+	 * to default probem other -ve value on error
+	 */
+	int (*probe_chip)(struct udevice *bus, uint chip_addr, uint chip_flags);
+
+	/**
+	 * set_bus_speed() - set the speed of a bus (optional)
+	 *
+	 * The bus speed value will be updated by the uclass if this function
+	 * does not return an error. This method is optional - if it is not
+	 * provided then the driver can read the speed from
+	 * bus->uclass_priv->speed_hz
+	 *
+	 * @bus:	Bus to adjust
+	 * @speed:	Requested speed in Hz
+	 * @return 0 if OK, -EINVAL for invalid values
+	 */
+	int (*set_bus_speed)(struct udevice *bus, unsigned int speed);
+
+	/**
+	 * get_bus_speed() - get the speed of a bus (optional)
+	 *
+	 * Normally this can be provided by the uclass, but if you want your
+	 * driver to check the bus speed by looking at the hardware, you can
+	 * implement that here. This method is optional. This method would
+	 * normally be expected to return bus->uclass_priv->speed_hz.
+	 *
+	 * @bus:	Bus to check
+	 * @return speed of selected I2C bus in Hz, -ve on error
+	 */
+	int (*get_bus_speed)(struct udevice *bus);
+
+	/**
+	 * set_flags() - set the flags for a chip (optional)
+	 *
+	 * This is generally implemented by the uclass, but drivers can
+	 * check the value to ensure that unsupported options are not used.
+	 * This method is optional. If provided, this method will always be
+	 * called when the flags change.
+	 *
+	 * @dev:	Chip to adjust
+	 * @flags:	New flags value
+	 * @return 0 if OK, -EINVAL if value is unsupported
+	 */
+	int (*set_flags)(struct udevice *dev, uint flags);
+
+	/**
+	 * deblock() - recover a bus that is in an unknown state
+	 *
+	 * I2C is a synchronous protocol and resets of the processor in the
+	 * middle of an access can block the I2C Bus until a powerdown of
+	 * the full unit is done. This is because slaves can be stuck
+	 * waiting for addition bus transitions for a transaction that will
+	 * never complete. Resetting the I2C master does not help. The only
+	 * way is to force the bus through a series of transitions to make
+	 * sure that all slaves are done with the transaction. This method
+	 * performs this 'deblocking' if support by the driver.
+	 *
+	 * This method is optional.
+	 */
+	int (*deblock)(struct udevice *bus);
+};
+
+#define i2c_get_ops(dev)	((struct dm_i2c_ops *)(dev)->driver->ops)
+
+/**
+ * i2c_get_chip() - get a device to use to access a chip on a bus
+ *
+ * This returns the device for the given chip address. The device can then
+ * be used with calls to i2c_read(), i2c_write(), i2c_probe(), etc.
+ *
+ * @bus:	Bus to examine
+ * @chip_addr:	Chip address for the new device
+ * @devp:	Returns pointer to new device if found or -ENODEV if not
+ *		found
+ */
+int i2c_get_chip(struct udevice *bus, uint chip_addr, struct udevice **devp);
+
+/**
+ * i2c_get_chip() - get a device to use to access a chip on a bus number
+ *
+ * This returns the device for the given chip address on a particular bus
+ * number.
+ *
+ * @busnum:	Bus number to examine
+ * @chip_addr:	Chip address for the new device
+ * @devp:	Returns pointer to new device if found or -ENODEV if not
+ *		found
+ */
+int i2c_get_chip_for_busnum(int busnum, int chip_addr, struct udevice **devp);
+
+/**
+ * i2c_chip_ofdata_to_platdata() - Decode standard I2C platform data
+ *
+ * This decodes the chip address from a device tree node and puts it into
+ * its dm_i2c_chip structure. This should be called in your driver's
+ * ofdata_to_platdata() method.
+ *
+ * @blob:	Device tree blob
+ * @node:	Node offset to read from
+ * @spi:	Place to put the decoded information
+ */
+int i2c_chip_ofdata_to_platdata(const void *blob, int node,
+				struct dm_i2c_chip *chip);
+
+#endif
+
+#ifndef CONFIG_DM_I2C
+
 /*
  * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
  *
@@ -451,4 +800,7 @@ int i2c_get_bus_num_fdt(int node);
  * @return 0 if port was reset, -1 if not found
  */
 int i2c_reset_port_fdt(const void *blob, int node);
+
+#endif /* !CONFIG_DM_I2C */
+
 #endif	/* _I2C_H_ */